The present invention relates to the preparation of substrates for optoelectronic devices and, more specifically, to a method of preparing an optoelectronic wafer for use with an active component. Some embodiments of the present invention are directed to fiber optic assemblies and individual components thereof which can be used in connection with optoelectronic devices.
Fiber optic technology is widely utilized in today's telecommunication and computer networks. One important aspect of fiber optic technology is the interconnection of optical fibers to optoelectronic devices, such as semiconductor lasers, photo-detectors, etc., wherein the optoelectronic devices either receive light signals from the optical fibers or the optoelectronic devices emit light signals into the fibers. A good optical interconnect between an optical fiber and an optoelectronic device requires high coupling efficiency (i.e., low loss of light from the coupling), ease of manufacture and a commercially viable manufacturing cost.
The demand for increased data transmission speed and the increase in computer processing speeds have driven the development of fiber optic technology. To achieve the necessary high density, rapid data transmission signals, optical interconnect assemblies are used in various communication and computer networks. Optoelectronic interconnects achieve higher rates of data transmission than electrical interconnects while maintaining lower power consumption.
In order to assemble high density optoelectronic interconnects, it is necessary to construct arrays of optical signal emitters and detectors which are interconnected by optical fibers. The emitters used to send the optical signals through the optical channels receive their input from electrical signals. These electrical signals can originate from an integrated circuit (IC) or the like. At the other end of the optical fibers are detectors which convert the received optical signals into electrical signals that can be processed. The connections must be extremely precise in order to avoid optical signal loss, and as the number of emitters and detectors increases, it becomes more difficult to maintain this precise alignment in constructing the connecting components. One known system of addressing this is disclosed in EP-0977064A (IMEC) in which alignment structures are formed on a faceplate. However, alignment of optic fibers with the faceplate is not addressed.
One type of light source that is used in fiber optic communication systems is the Vertical-Cavity Surface-Emitting Laser (VCSEL) which is essentially an extremely small laser (about three microns long). The VCSEL is generally constructed using two mirror stacks located on opposite sides of an active region. The mirrors reflect back and forth the light generated in the active region. This reflection back and forth results in a “stimulated emission” that produces light at a single wavelength or color. Such “coherent” emission is the hallmark of lasing technology. Conventional VCSELs in production today are typically based on a substrate of gallium arsenide. To form an array of light emitters, a semiconductor wafer consisting of multiple groups of VCSELs is typically produced. VCSELs may be top emitting or bottom emitting through the substrate, if a transparent substrate is used. Other types of light emitters, such as LEDs can also be used, if desired. Semiconductor wafers can be produced which include a large number of VCSELs grouped in precision arrays, which are then separated into individual arrays and processed and finished into optoelectronic components which must be connected to an active component in order to be able to emit optical signals.
The VCSELs are typically wire bond mounted to the active components, such as VLSI chips or the like, and an optical window is typically positioned over the VCSELs to protect them from damage as well as allow optical signal transmission from the VCSELs for communication with remainder of the optoelectronic system. However, assembly of damaged VCSELs to the active components and difficulty in positioning the VCSELs on the active components results in some of the VCSEL and active component packages being scrapped during manufacturing. Additionally, the mounting of individual optical fibers to the optical elements having a window facing the VCSEL, has been difficult to reliably accomplish in a cost effective manner. One known method is to utilize perforated alignment plates to align the fibers, as disclosed in U.S. Pat. No. 5,135,590, which is assigned to AT&T.
It would be advantageous to provide a method for VCSELs to be mounted on active components of ICs that reduces the need to scrap active components due to VCSELs being inoperative due to damage or defects incurred during formation, that simplifies the proper alignment of the VCSEL wafer with an optical element, and that allows for a better connection between the active component and the associated wafer. Additionally, it would be advantageous to provide an optical element to which an optic fiber can be readily attached. Furthermore, it would be advantageous to develop a method of mounting VCSELs to active components that is more efficient and cost effective than the prior known method.